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In this short video, we are going to discuss the role

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of PSMA PET in prostate cancer.

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And I'm gonna give you some brief context.

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PSMA PET has been recently approved by the FDA

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and it's a tracer that we are now seeing a lot in practice.

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It has a specific role.

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Uh, we don't do PSA pity for all the patients

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that have prostate cancer.

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When it really makes a difference is in those cases

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where there is the no disease,

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but patients have a high risk malignancy,

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those would be cases with Gleason score greater than seven,

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and also in the scenario of biochemical recurrence

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or castration resistant prostate cancer,

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as we can identify a small side of disease more

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sensitively than other techniques.

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So I have summarized the clinical applications,

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the first three I just mentioned.

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The fourth would be to assess for eligibility

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for radioligand therapy.

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And this is a new FDA approved, a therapeutic agent

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in which essentially changing the F 18

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or gallium 68, uh, group by a LUTETIUM 1 77.

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We have now a targeted therapeutic agent for

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treating metastatic prostate cancer that has failed

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other therapies.

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It's also written in the literature intra prostatic

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localization and usefulness for guiding biopsy.

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But, uh, this is probably of all the indications, uh,

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the list comment, I included these.

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Um, so you could have an overview of the different stages

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where we can help patients.

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We can help them throughout their oncologic history from the

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initial diagnosis to once they have recurred

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after initial therapy, and if they progress throughout

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different lines all the way to at the end of

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the therapeutic agents, we now have that additional

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specific radioligand.

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So for initial staging in a patient with high risk,

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these are patients that have prostate gland, the majority

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of them will have a prostate.

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MRI. Obviously these two imaging, uh,

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modalities are complementary

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and, uh, you will find

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that more often than not you will find

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concordance in findings.

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But again, because we are doing molecular imaging,

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we might be able to detect areas of, uh, small volume

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of disease in a very specific way.

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We have a great value in a staging

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the lymph nodes of these patients.

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And I'm putting here an example where you can see

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that there is clear PCMA uptick in

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that ator space on the left that corresponds

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with a tiny lymph node.

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In conventional imaging,

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this would have never been called positive.

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So this is the greatest advantage of PSMA pet.

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PSMA PET is capable of depicting these small lymph nodes.

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And in one study it was reported

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that 78%

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of the PSMA avid lymph nodes were smaller

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than eight millimeters.

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Same goes with distant disease.

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Here I'm showing you intense PSMA uptake in an OUS lesion

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that has a very faint correlate.

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And as we have seen in other cases,

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we can actually find disease when there, there's still no CT

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lesion for us to describe

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or identify in other modalities.

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In cases of restaging or biochemical recurrence.

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PSMA HIT has helped

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identified areas of a small volume of disease.

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I have included the definition

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of biochemical recurrence in both the scenarios.

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The first, uh, after the patient has gone radical

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prostatectomy in which is described as a PSA greater

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or equal than a 0.2 or after radiation therapy

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or brachytherapy in which you will still have prostate.

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The PSA definition of biochemical recurrence is greater

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or equal than two nanogram per milliliter

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or greater depending on the Nazi or PSA.

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And this is a definition

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by the American Urological Association.

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Now, whether you do an F 18 PSMA

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or an gallium 68 PSMA,

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it's depending upon the availability of,

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uh, the radio pharmacy that provides you with the tracers.

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As I think practically speaking, there isn't

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a large difference between the two agents.

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However, there are no clinical trials

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or studies comparing the two.

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So I think that if you do one

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or the other, it would be mostly based on availability.

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Can we detect everything with PSMA?

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Well, the reality is that we don't.

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I'm gonna show you a couple of clinical trials, uh, in which

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they made an certification

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of a detection rate based on the PSA.

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The first one is done with Gallium 68

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and uh, you can see how increasing levels

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of PSA you have a higher detection rate,

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but it's never a hundred percent.

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Obviously with PSA greater

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or an equal to five, you should expect

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identifying disease.

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Same goes with a condor clinical trial that was performed

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with the F 18 tracer F 18, uh,

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PSMA also,

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they did an stratification based on PSA levels

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and they have three readers.

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And greater

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or equal to five has a high detection rate, close

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to a hundred, but not a hundred percent.

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So whenever you have a negative PSMA, it could be

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that disease is still there, but you're not detecting it

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because you fall into those cases were disease was

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not, uh, seen.

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10% of the cases of adenocarcinoma of the prostate

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will not be PSMA avid.

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The other important information we can add in

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This cases, the accurate nodal

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Staging. And for that,

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I think it's important to have in mind

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what represents a true pelvic lymph node versus distant

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pelvic nodal disease.

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You might find mild discrepancies between anatomist

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and radiologist or surgeons,

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but I think what I'm showing you here is the mostly

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used classification.

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Pelvic lymph nodes include those in the internal iliac,

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sterile iliac and ator spaces, as well

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as those sacral lymph nodes and hypogastric lymph nodes.

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Outside of that, this is distant pelvic

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Disease, Uh, including the inguinal lymph nodes

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and above the iliac bifurcation in the retroperitoneum,

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posterior mediastinum and supraclavicular ations,

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and then beyond like intrathoracic, for instance.

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So now let's move on and let's review several cases

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and let's apply these concepts.